Dear Car Talk:

I don’t drive my car very much and worry about the battery dying, as it has twice this week. What do you think about solar battery chargers for my 2008 Altima? It would be great not to waste time worrying about batteries! — Marjorie

I’ll be glad to demean solar battery chargers, Marjorie, but first I’m more concerned that there’s something wrong with your car. Your battery shouldn’t be dying twice a week if everything is working properly.

So start by having your mechanic test the battery and your car’s charging system. The battery might not be charging when you drive. Perhaps it’s more than 5 years old and can’t hold a charge anymore. Or maybe something is staying on and draining the battery while your car is parked.

We’ve also seen situations where owners will accidentally hit the stop-start ignition button twice when shutting off the car, which puts the car into accessory mode. If the car remains in accessory mode, electronics such as the radio and heater fan will continue to run and drain the battery.

In terms of chargers, solar chargers put out about 500-1,500 milliamps. So even at the high end, under perfect, sunny conditions, it’s adding about twice as much current as your car is draining just by being parked.

And because conditions are rarely perfect, you’ll just barely be replacing what the computer, the emissions system and the alarm are drawing when the car is off.

So if your battery is going stone-cold dead twice a week, a solar battery charger is not going to make up the difference.

If everything were working properly, and you were the kind of person who parked your car for weeks at a time and lived in a particularly sunny clime, a solar charger might be enough to keep your battery charged up.

But unlike conventional, plug-in trickle chargers (also called battery tenders) that serve the same purpose, solar chargers have no automatic shut-off switch. So, while unlikely, it’s possible, under certain conditions, to overcharge your battery with a solar charger. You’d have to be extremely lucky to get enough juice out of it to have that happen, but it’s possible.

But start by figuring out what’s wrong with your Altima’s electrical system, Marjorie. And once you get that fixed, you may find you don’t need any battery charger at all.